I recently replaced the brake fluid cap ( a new original jag part ) I hooked up both sides + and - and the light on the dash stays off until you close the hood . with the hood closed the light stays on ..................any ideas on how keep the light from coming on ???

 

closing the hood should not make any difference in the operation of the Brake Fluid Warning light. Was it doing it before you replaced the cap?

 

yes the old cap was cracked and it was doing the same thing .......I did notice when you press down on the little metal pin on top of the cap , the dash light goes on ...........so when the hood is closed it probably pushes down on the pin

 

I've had this problem on several Ser III cars. In some cases the hood itself, when closed, physically comes in contact with the rubber cap/switch and closes the switch contacts. It's just a matter of a slight repositioning of the cap....turn it a bit to the the right or left. Takes a little experimenting. Or you may have to slightly adjust the hood ...just a smidge...so it doesn't close quite so far.

Cheers
DD

 

I wonder if the metal of the hood is coming in contact with one of the wire terminals, the cap should have a rubber cover over it.

Also, if you disconnect one of the cap's wires, does the light go off?

 

Tis a weird little switch. I've messed with mine on and off for a few years!! A float is immersed in the fluid. A pin not only guides it but also aligns the on/off contacts.
If that pin isn't slick and shiny, it will stick down or up. And, the little fake vinyl capo can effect it's up down movements.


When the pin is down, it closes the contacts and the dash light says low fluid. That may or may not be true.


I've a spare with a corroded pin. I've worked on it from time to time to get it to slide smoothly the one on y car is fine, except that one of the spade connectors busted off!


I've even considered making one from two. But, visual works just fine now. especialy since I am n o longer losing fluid from seeping rear calipers!!!


As already said, it is a finagle thing til it works.


Carl

 

I need to pick up the rubber cover ...........that should solve the problem , cause the little post is touching the hood

 

...or put a piece of duct or foam tape at the point of contact on the hood side and see if that stops the light from coming on

 

Although my problem is somewhat related to this thread, I have the issue where the light will not work at all! I have shorted the 2 wires on the cap. and still no light. When I take one wire (I believe it was black/yellow) and ground it, I get the light on the dash when the key is turned on (engine not running); however, it does not go off until I break the ground connection or shut off the key! I believe my problem may be downstream of the fill cap i.e. the black wire.....not sure where this is going but I assume it is looking for ground somewhere? Any comments/expertise with this "no-glow" brake warning light? For general info, brakes were worked on by previous owner.....new pads on rear. Also, emergency brake does not work at all! Any and all comments appreciated. Thank you.
1988 Vanden Blas V12; 130,000 km.

 

Wayne:


Same guy did my rear calipers!!! Now, no hand brake. and, I did provide new pads for it as well as the service brakes. Too late now to fuss. I rarely apply them anyway.... either of my cars.


The little device that manualy clamps the teeny pads on to the rotors is
intricate of many parts, that must be correctly assembled and intricately adjusted.


There is a detiled posting somewhere on this forum as to dealing with them and even improving the action.


A fellow in France as I recall....


Greg ?????


Carl

 

The hood brace near the top of the MC location hits the rubber cap enough to press down on the MC causing fluid to leak out the rubber seals between the reservoir and MC.

I just used a large set of adjustable pliers and "formed" the area above the MC enough for the needed clearance.. now no problems..

Wires from cap should face in the direction you desire after "adjusting" for the needed hood/MC clearances.

 

Thank you Carl for the response. This may explain why the emergency brake is not working at all, as I am suspicious that the brakes were perhaps not done correctly and to my knowledge, the pads for the emergency brake were not changed. This should have no impact on the brake warning light, right? My emergency brake light does work, but the emergency brake does not engage. I have adjusted the travel in the cable and all appears good with the cables right up to the calipers. I expect I will have to disassemble and re-work; the rear discs need to be replaced anyway.
Any thoughts on the brake warning light for fluid level and differential pressure sensor......it will not come on at all unless I short the one feed wire to the master cylinder cap, with key turned on. So, I know the warning light bulb is OK, but it just will not come onwhen I turn the key (without manually shorting the wire). It also does not come on when I have low fluid, or, if I connect the 2 wires on the cap.....that should be the same as a closed switch on the cap, but, I get no warning light! Any thoughts?

 

Wayne:


My long distance suspicions are that the contacts within the
low brake fluid switch are corroded. I'm not sure if it can be disassembled for contact cleaning and reassembled. Or perhaps cleaning the contacts by spraying in contact cleaner and exercising them. Off the car, of course, to avoid fluid contamination.


I just rely on my Saturday morning Motor stables. Check functions and levels on both cars.


Carl

 

My brake warning light came on. The fluid level is fine. I searched and found this thread and Doug’s post. After reading the post, I went out and started the car and the brake warning light came on. I lifted the hood and it went out! I unscrewed the brake fluid cap and put it back on but in a slightly different angle than before. I closed the hood and no more light!

Thank you, Doug!